FR2549713A1 - DENTAL ANCHORAGE THREADED - Google Patents

Abstract

THE INVENTION RELATES TO A THREADED DENTAL ANCHOR THAT IS AUTOMATICALLY SCREWED INTO A HOUSEHOLD CHANNEL IN A TOOTH. IT INCLUDES AN EXTREME PROXIMAL MANIPULATION TRUNK 12 ALLOWING TO SCREW ONE OR THE OTHER OF TWO THREADED ANCHORING TRUNKS 16 SEPARATE BY A PART 38 OF REDUCED THICKNESS ALLOWING THEIR TO BE SEPARATED FROM ONE OF THE OTHER BY BREAKAGE OF THIS PART 38. THE THREADS OF THE ANCHOR TRUNKS ARE ADVANTAGEALLY SPACED SO THAT EACH TRUNK HAS BETWEEN 24 AND 40 THREADS PER CENTIMETERS. IN ADDITION, THE PILOT DISTAL END 36 OF THE ANCHOR TRUNKS IS EXTENDED IN THE AXIAL DIRECTION OVER A DISTANCE APPROXIMATELY EQUAL TO THE PITCH OF THE NETS. FIELD OF APPLICATION: DENTAL RESTORATION.

Description

The invention relates generally to dentistry, and more

  particularly anchors or dental pins used to retain or strengthen

dental restorations.

  When the crowns of the teeth are seriously decayed or fractured, there are difficulties in conventional preparations, to ensure effective retention of the restoration techniques are available allowing the use of small anchors 10 or small pins and / or In general, the carious or fractured portion of the tooth is removed so that an excavated surface is available. Then, one or more blind channels are formed in the remaining portion of the tooth. penetrating the dentine from the exposed excavated surface Pins or pins of reinforcement or anchoring are then inserted into the channels There are many types of anchors including self-anchoring anchors, pins 20 which are inserted and then retained by cementing, or

  forced-fit anchors retained by a tight fit Such anchors are inserted so that a free portion protrudes above the excavated surface.

  A superstructure is then constructed on the exposed excavated surface where it is retained by means of the trunk

  This method of constructing the suprastructure on the toothing is described in numerous patents and technical articles, for example in U.S. Patent No. 3,434,209.

  The particular dental pins or anchors that are used to connect and anchor the superstructure to the infrastructure are of various types. US Patent No. 3,675,328 discloses a dental anchoring to a plurality of threaded sections that can be sectioned to one another. US Pat. No. 3,675,329 discloses a pin or anchor pin having a head protruding above the infrastructure to be embedded in the superstructure and to oppose its movement. Another dental anchor, described in U.S. Patent No. 4,053,982, utilizes an L-shaped manipulation section which can be loosed in a dental tool so that the anchor can be manipulated into the infrastructure and Also, to assist in the restraint of the suprastructure. Various types of manipulator sections may also be provided on the dental anchor, as described in the US Pat. No. 4,202,101 which also discloses a hand-held drive member for use in

  in the insertion into the dental structure.

  The patent of the United States of America

  No. 3,861,043 discloses a dental pin or pin used in the construction of a suprastructure on a tooth, the pin having a shank having a groove at its lower end, the remaining portion of the shank being threaded.

  U.S. Patent No. 6,417,569 discloses a dental pin or pin having spaced threads formed on two opposed coaxial rods, separated at their center by an enlarged section serving as a rotation handle. a large recommended diameter for the pins and a recommended height for the nets; however, there is no suggestion as to the number of threads per centimeter or the pitch of the threads. United States Patent No. 4,334,865 discloses a dental pin or pin having a threaded rod whose thread is of the sawtooth type and an expanded collar serving

support element for the screw.

  U.S. Patent No. 4,365,958 discloses a dental drill and a dental anchor which are combined with each other and separated by a stop member so that the drill forms

  its own hole in the dentine of the tooth so that the anchor pin is fixed in a single insertion operation However, like the aforementioned patents, the latter patent gives no information regarding the number of threads per centimeter or the pitch of the nets.

  In laying anchorages of this type, it is obviously essential that the practitioner avoids imposing on the teeth the stresses that may appear during the laying process. Unless such precautions are observed, this can result in The reduction or complete elimination of this risk has proved extremely desirable. To eliminate this risk, it has been found desirable to use means which reduce the possibility of occurrence of excessive insertion stresses by avoiding that the anchor comes to heel against the closed end of the canal and that it generates,

  if necessary, undesirable constraints.

  Because of the importance of these suprastructures in tooth restoration, many technical studies and research programs have focused on determining the best type and technique of pin retention. It has been necessary to evaluate insertion anchors in materials that can replace dentin. These models do not necessarily reproduce

  the various physical characteristics of the dentin, although generally a high modulus plastics material is used as the dentin substitute test material.

  Using these techniques, the researchers studied various parameters affecting the restraint and insertion The parameters that were studied in detail include the type of pin or anchor pin, the diameter of the pin, its depth , the number of pins, the effect of cavity varnish and various dental cements, and the restraint in a

-2549713

  dental amalgam, etc. For example, it appeared that anchorages

  Self-tightening offers the largest restraint among the various types tested. It has also been found that the restraint increases with the diameter of the spindle.

  A greater depth of insertion also increases the restraint; however, the self-tightening anchors have been found to provide the best retention at the same depth in comparison with friction lock anchors or cemented pins.

  The tests also focused on the number of anchors to be used, the angle of insertion and the technique

  used for the insertion of anchors.

  In spite of all the above-mentioned different tests and procedures, the use of dental anchors has not yet been as effective and satisfactory as is theoretically possible. One of the most obvious reasons for the lack of success is that Test models do not accurately reproduce dentin characteristics In addition to having a wide range of modulus values and different compressive and tensile strengths, dentin has a particular histological structure including directional properties. in addition, the characteristics of dentin vary and, therefore, the

  The anchoring technique, for insertion, must have such characteristics that it is constantly useful and that it avoids the risk of injury to the adjacent toothing. Therefore, the various tests whose results are based on Dentin replacement, while providing conclusions - which may be useful for certain properties of dentin, do not suitably interest all the particular properties of dentin and are therefore not as effective as the theory intended.

  The most important aspect of using dental anchors is to ensure the proper degree of

25497 1 3

  withholding or securing and, at the same time,

  reduce the degree of compression of the dentin and eliminate the harmful effects on the adjacent dentine.

  When anchors of the prior art, and particularly anchors of the self-tightening type, are improperly inserted into the blind channels formed in the tooth structure, undesirable stresses appear in the existing dentine, particularly in the closed end or at the bottom of the support part during a total insertion.

  One aspect of threaded anchors that has not generally been investigated so far is pin or pin nets. In most threaded anchor studies, standard threads are used for a given pin diameter up to 10 mm. at present, it has not been realized that the number of nets per centimeter could significantly influence anchor pin attachment and the degree of stress and

deterioration of dentin.

  It has now been found that when inserting a threaded anchor pin into a dentine-type material, a decrease in the number of threads per unit length gives better results than those obtained with a pin. Threaded anchor having a greater number of threads per unit length. Using such a reduced number of threads per unit length, better retention or fixation of the anchor pin is obtained while reducing the undesirable stress of dentin. In addition, the torque needed to insert the anchor is lower

  and the insertion speed is increased because the number of rotations required to insert the anchor at the desired depth is reduced, as is the magnitude of the stress induced during the insertion operation itself.

  In addition, a more efficient method can be used to fabricate threaded dental anchors whose thread count per unit length is reduced; the small diameter of the threaded dental anchor may be increased relative to that of the prior art dental anchors, thereby enhancing the dental anchorage of the present invention. In one embodiment of the invention, to reduce the degree of stress in the bottom of the canal in the tooth, the pilot or distal end of the dental anchor has been lengthened to space the bottom threads. of the channel, the taper angle of the pilot or distal end relative to the circumference of the dental anchor of the present invention being decreased relative to the taper angle of the

  dental pins of the prior art.

  In another embodiment of the invention, to further reduce the degree of stress in the surrounding tooth structure, a trapezoidal type thread is used which allows a slight increase in the number of threads per unit length to give a reduced step. and also allows an increase in the small diameter of the spindle to increase the retaining or fixing capabilities of the spindle while

  reducing dental stress.

  The dental anchor according to the invention has been further modified to further reduce the degree of stress generated in the root canal of the tooth, wherein each of the modified embodiments of the dental anchor may include a stopping member. disposed along its length to limit the insertion depth of the dental anchor into the channel that penetrates the dentin from the excavated surface of the tooth These stop members can be formed in many ways on the anchor dental, for example by the realization of a non-threaded section, 35 by deformation, discharge, misalignment, stamping,

fulfillment and others.

  The subject of the invention is therefore a pin or a dental anchoring pin which eliminates the problems indicated above, posed by the anchoring pins of the prior art. The subject of the invention is furthermore a pin or pin of dental anchor of the threaded type,

  which makes it possible to obtain better results than the self-locking dental pins of the prior art.

  The invention also relates to a self-locking dental pin or pin that has fewer threads per unit length than the comparable dental pins of the prior art. The invention furthermore relates to a pin or pin A further object of the invention is to provide a dental anchoring pin or pin having a special thread which provides improved support strength and to reduce the degree of dentin damage upon insertion. improvements over the dental pins of the prior art, and in particular a pin or dental anchoring pin 20 whose small diameter is greater than the small diameter

  comparable dental pins of the prior art.

  The subject of the invention is also a pin or dental anchoring pin having a distal or pilot end elongate with respect to the pilot or distal ends of the comparable dental pins of the prior art. The subject of the invention is also a pin or pin dental anchoring device which comprises a depth-limiting section in order to avoid reaching the abutment of the dental anchoring pin at the bottom of the channel formed in the infrastructure and thus to avoid

  the risk of constraints or cracks in the infrastructure, especially at the bottom of the canal.

  The subject of the invention is also a dental pin or pin as described above, in which the depth-limiting section comprises an abutment member formed on the spindle by a non-threaded section, by deformation, backflow. The invention further relates to a dental pin or pin having a trapezoid-type net having a particular pitch and having a small diameter greater than the small diameter of the comparable dental prongs. DESCRIPTION OF THE PREFERRED EMBODIMENTS

of the prior art.

  Briefly described, the invention relates to a self-sliding dental pin or pin having a proximal head or end having means for mating it to a complementary drive tool. A stem extends from the proximal head and / or end. carries a plurality of threads defined by axially spaced ridges, the rod having fewer threads per unit length and a smaller diameter greater than a prior art conventional and comparable dental anchor pin. The pilot end

  or distal from the shaft may be elongated so that the threads are spaced apart from the distal end. In one embodiment of the invention, a trapezoidal type net is used.

  In a modified embodiment of the invention, the dental pin or pin includes stop means constituting a depth limiting section which limits the depth of insertion of the anchor pin into the channel formed in the infrastructure of the tooth and which prevents any contact between the distal end and the bottom of the channel, the abutment means being arranged on the axial length of the anchor pin, at a distance from the pilot or distal end 30 of the This embodiment of the invention comprises a non-threaded body section; another embodiment comprises a stamped or stamped body section; another embodiment comprises an expanded body section formed by repressing; and another embodiment of the invention comprises an enlarged body portion extending axially. The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting examples and in which: FIG. 1 is a perspective view of an embodiment of the threaded dental anchor according to the invention; Figure 2 is an elevation, partly in section, showing the distal end portion of the threaded dental anchor of Figure 1; Figure 3 is an elevation, in partial section, of a tooth or toothing on which an excavated surface is formed prior to the construction of a suprastructure, this view illustrating the dental anchors of the prior art inserted into the tooth; Figure 4 is an elevation, in partial section, similar to that of Figure 3, illustrating the dental anchors of the invention inserted in the tooth or in the toothing; FIG. 5 is an enlarged scale elevation, partially sectioned, for comparing the dental anchor of the prior art with the embodiment of the dental anchor according to the invention, shown in FIG. 1, these anchors being inserted in the tooth or toothing; Figure 6 is a partial elevation illustrating a modified embodiment of the threaded dental anchor according to the invention; Figure 7 is a section along the line 7-7 of Figure 6; Figure 8 is a partial elevation of another embodiment of the threaded dental anchor according to the invention; Figure 9 is a section along the line 9-9 of Figure 8; Figure 10 is a partial elevation of another embodiment of the threaded dental anchor according to the invention; Figure 11 is a section along the line 11-11 of Figure 10; FIG. 12 is a fragmentary view of another embodiment of the threaded dental anchor according to the invention; Figure 13 is a section on the line 13-13 of Figure 12; Fig. 14 is an elevation, partly in section, showing the channels formed in the tooth 10 shown in Figs. 3 and 4; Fig. 15 is an elevation, partly in section, showing the modified dental anchors of Fig. 6 being inserted into the tooth of Fig. 14; Figure 16 is a perspective view of another embodiment of the threaded dental anchor according to the invention; FIG. 17 is a partial perspective view showing the upper end portion of a variant of the threaded dental anchor according to the invention; FIG. 18 is a perspective view showing the modified upper section of another embodiment of FIG. the threaded dental anchor according to the invention; Fig. 19 is an elevation, partly in section, showing the distal end portion of the threaded dental anchors of Figs. 16 and 18; and Fig. 20 is an enlarged, partially sectioned elevation comparing the dental anchor of Fig. 1 to the dental anchor of Fig. 16 or Fig. 18 when such anchors are

inserted into the tooth or toothing.

  In the various figures of the drawings, the.

  The same reference numerals denote the same elements. FIG. 1 represents a dental anchor according to the invention. The dental anchor 10 comprises a proximal head or end which forms a section.

25497 1 3

  extreme manipulation 12, an intermediate section or second threaded anchor section 14, and a section

  lower or first threaded anchor section 16.

  The end portion 12 of manipulation comprises a cylindrical body 18 comprising two lugs 20, 22, made by stamping or stamping to form a torque transmission mechanism, the lugs 20, 22 protruding transversely outwardly of the cylindrical body 18 to form flat surfaces on each side and rounded edges. The upper end of the handling section 12 has a conical end 24 which assumes the function of a proximal driver for the insertion of the handling section into a dental tool or sleeve. The end section 12 of manipulation is connected to the second section. 14 anchoring by a brittle portion 26 of reduced thickness, so that the handling section 12 can be severed from the second anchor section 14 after it has been inserted into a channel.

the infrastructure of a tooth.

  It should be noted that the extreme stretch

  12 of manipulation is similar to the extreme handling section described in the aforementioned patent N 4 202 101, and that it is represented only by way of example.

  Therefore, many other types of extreme handling sections can be used, as is well known in the art and as described in the aforementioned patents. Any extreme handling section of the prior art can therefore be used, provided it is designed to be received in a mandrel 30 of a conventional dental handpiece or key

  or other conventional hand training device.

  As described in the aforementioned patent No. 4,202,101, the end portion 12 of manipulation as shown in Figure 1 is designed to be received in a rod 35 or a sleeve, preferably plastic, intended to be housed in the room dental hand or

  in a manual drive.

  The first and second sections 16 and 14

  Anchoring is analogous and, therefore, a complete description of only one of these anchoring sections 5 suffices. It should be noted that a dental anchor having two anchor sections connected to each other is described. Thus, only the differences of the present invention with respect to this prior embodiment will be indicated hereinafter.

  Each of the anchoring sections 14 and 16 comprises a body 28 carrying a helical thread 30 having ridges 32. The anchoring sections 14 and 16 have a large diameter of about 0.61 mm and a small diameter of about 0.48 mm so that the height of the net is approximately 0.063 mm The number of nets per centimeter is between 24 and 40, a value of 33 nets per centimeter being preferred, giving a pitch of approximately 0.305 mm Therefore, each of the anchor sections 14 and 16 having a length

  about 4.50 mm, it carries about 14 nets.

  Each of the anchor sections 14 and 16 has a chamfered upper end 34 and a tapered opposed pilot or distal end 36. The curbed end 32 has a chamfer of 45, so that the chamfered end 34 of the second anchor section 14 is connected to the end portion 12 of manipulation so as to form a portion 26 of reduced thickness, and that the chamfered end 34 of the first anchoring section 30 is connected to the pilot or distal end

  36 of the second anchor section 14 forming with it a second brittle portion 38, of reduced thickness.

  It should be noted that the second portion 38 of reduced thickness has a diameter or a dimension smaller than that of the first mentioned portion 26 of reduced thickness so as to ensure the breaking of the second portion 38 of reduced thickness before that of the portion 26 of reduced thickness, as described in the patent

No. 3,675,328 cited above.

  As shown more clearly in FIG. 2, the pilot or distal end 36 tapers downwardly from body 28, at an angle of about 20, to form an elongate structure. distal to the axis of the anchor section is about 0.305 mm, which is approximately equal to the pitch of the thread 30. In addition, the dimension of the small diameter portion included

  between the adjacent thread legs 30, this dimension being indicated at 40, is about 0.241 mm, and the distance 41 between the crests 32 of adjacent threads is about 0.27 mm, so that each of the threads 30 has, at its crest, a flat 42 of about 0.038 mm It is thus clear from the foregoing description

  and FIG. 2 that the distance 40 between the feet of the threads 30, at the small diameter, is at least twice the thickness of the root of the thread 30 at the small diameter, so that the ratio of the distance (0, 24 mm) at the thread pitch (0.305 mm) is about 4: 5. It should be noted that, although the dental anchor 10 as shown in FIG. 1 has two anchor sections 14 and 16, the invention can also be applied to dental anchors having only one section of In addition, the invention can also be applied to dental anchors whose extreme handling section is fixedly connected to the threaded anchoring section, as described above.

  in the aforementioned patent No. 3,434,209.

  Figure 3 illustrates a view of the prior art, similar to that given in the aforementioned patents, showing a tooth or toothing 44 housed in the soft or gingival tissue 46 of the human gingiva.

  As is well known to those skilled in the art, the body 48 of the tooth 44 is made of dentin and encloses

  A pulp chamber 50 The dentine protruding from the gingival tissue 46 is covered with an enamel layer 52.

  To prepare the toothing 44 for the construction of a superstructure, part of the enamel 52 and a portion 5 of the dentin are excavated in order to eliminate the decay and the damaged tooth structure in order to form a denture.

  excavated surface 54 from which decay is eliminated.

  The first step in forming the suprastructure is to make several channels 56, preferably 10 non-parallel, in the dentine or body 48, from the uncovered excavated surface 54 as shown in FIG. 14. For this purpose, a helicoidal drill conventional 55 is depressed into the dentine in a conventional manner, the drill having a large diameter which is preferably about 0.533 mm and an end taper angle of about 118 to form a corresponding channel after the requested number of channels The piloted or distal end of each anchor 58 has a chamfered transverse end surface 60 that has a taper of about 30 with the body. The other end of the dental anchor 50 has a chamfered transverse end surface 62 which has a taper of about The chamfered end surfaces 60 and 62, when connected to each other to form a dental anchor, define a brittle portion 64 of reduced thickness which allows the two threaded anchorages to be severed from one another. other when the first anchor is housed in the tooth It is obvious that the dimension 66, representing the large diameter of the pierced channel 56, is smaller than the large diameter of the threaded dental anchor 58, so that this dental anchor 35 can be self screwed in the channel 56 The dental anchors of the prior art comprise about 50

nets per centimeter.

  It has been indicated, with reference to FIG. 3, that the anterior dental anchors 58 are not always fully inserted into the channels 56, their insertion being not constant because of the excessive resistivity that can occur while the dental anchor 58 is screwed into the channel, the portion 64 of reduced thickness may shear too early, so that the dental anchor 58 is not fully housed in position and the chamfered end surface 60, which is about 0.076 mm, is at a distance from the bottom of the channel 56 Therefore, although it is desired to fully insert the dental anchor 58 to the bottom of the channel, this insertion is not necessary.

always obtained.

  FIG. 4, which is similar to FIG. 3, shows two dental anchors 10 according to the invention totally inserted into the channels 56 formed in the tooth 44, and a third dental anchor 10 being inserted in a third channel 56. 20 of the structure of the dental anchor 10 according to the invention, which comprises the thread 30 and the pilot or distal end 36, its automatic screwing is faster and the stresses are reduced during the insertion, and the latter is uniform to obtain the desired degree of insertion of the dental anchor into the tooth channel 56. In addition, the portion 38 of reduced thickness between the first and second

  anchoring sections 16 and 14, is more visible than in the prior art, so that its shear point 30 can be more easily determined.

  FIG. 5 is an enlarged sectional view of a body 48 of the tooth in which the channels 56 are pierced, each channel having a bottom 68. As shown clearly, the thread 70 of the dental anchor 35 58 of the prior art is closer to bottom 68 of

  canal that the threading 30 of the dental anchor 10 according to the invention, the thread or thread 30 being distant-

  Due to the extension of the pilot end 36 of the dental anchor 10 In addition, the thread 70 of the prior art dental anchor 58 tends to further crush the dentin of the tooth than the thread 5 of the tooth. In addition, as clearly shown, there is more dentin between adjacent threads of the thread 30 than between adjacent threads of the thread 70 of the anterior dental anchor. This larger amount of dentin between the adjacent threads The thread 30 reduces stress and provides better retention or fixation when the dental anchor is cut or bent prior to the construction of the suprastructure on the tooth, with the amount of dentin between the adjacent threads being in a ratio of minus 2 to 1, with respect to each thread of the thread, because of the ratio of 4 to 5 of the width of the part of small diameter between the feet of net, at the pitch of the threads It should also be noted that the small diameter 72 of the threaded portion of the dental anchor 20 according to the invention is larger than the small diameter 74 of the anterior dental anchor 58, which gives greater strength to the anchor

dental 10 according to the invention.

  FIGS. 6 to 13 show variants of the dental anchor 10 described above, in accordance with the invention. Each of these different embodiments of the dental anchor comprises an abutment or stop member, preferably arranged about the middle of its length and intended to limit the depth of insertion of the dental anchor into the channel that enters the dentine or body 48, from the exposed excavated surface 54 of the tooth 44. stop or abutment members may be formed on the dental anchor in any one of a number of ways, for example by making a stump

  non-threaded, by deformation, displacement, misalignment, stamping, expansion and others as described above.

  Afterwards, it should be noted that once the stop member bears against the edge of the mouth of the channel, its entry into contact with the edge prevents any further rotation and triggers the automatic shearing mechanism. the dental anchor, so that the reduced thickness portion of this anchor is sheared and the insertion operation of the anchor

dental stops then.

  Figure 6 shows at 110 a modified embodiment of the dental anchor according to the invention, similar to the dental anchor 10 and having similar anchoring sections 114, 116 which each have a thread or helical thread 30 to crests 32, and a chamfered upper end 34 and an opposing conical pilot or distal end

  36, so that the connected ends 34, 36 form between them a brittle portion 38 of reduced thickness.

  Therefore, the structure described so far is the same as previously described for dental anchoring. Furthermore, it does not seem necessary to illustrate the proximal end or the extreme manipulation section which is also identical to that

previously described.

  At approximately the middle of the length of each of the anchor sections 114 and 116 is a non-threaded body portion 118. This unthreaded body portion has an axial length of about two or three threads of the thread. in Figure 7, the unthreaded body portion 118 has a diameter of about 0.61 mm, which is larger than the small diameter 72 of the remaining threaded portions 114 and 116, so that the non-threaded body portion 118 constitutes a stop member for limiting the insertion depth of the anchoring sections 114 and 116 in the channel formed in the tooth, as described below. Fig. 8 shows 210 another modified embodiment of the dental anchor according to the invention which, as above, is analogous to

  at the dental anchor 10, comprising similar anchorage sections 214, 216 each carrying a helical thread 30 which has ridges 32, these sections each comprising a chamfered upper end 34 and an opposite conical pilot or distal end 36, of The connected ends 34, 36 form between them a brittle portion 38 of reduced thickness.

  As before, the structure described so far is therefore identical to that described above for the dental anchoring. Furthermore, it does not seem necessary either to illustrate the proximal end or the extreme manipulation section which is also

  identical to that described above.

  Substantially in the middle of the length of each of the anchor sections 214, 216, these anchor sections are stamped or stamped to include a flattened and enlarged body portion 218 that projects transversely outwardly into opposite directions, of each section so as to have flat surfaces on each of its sides and rounded edges, as shown in FIG. 9 Thus, since the body section 218 has a transverse dimension greater than the small diameter 72 or thread 30 of the remaining threaded sections 214, 216, the body 218 constitutes a stop member which limits the depth of insertion of the anchor sections 214, 216 into the channel formed in the tooth, as described

above as an example.

  Figure 10 shows at 310 another modified embodiment of the dental anchor according to the invention which, as before, is similar to the dental anchor 10, having similar anchoring sections 314, 316 each carrying a thread helicoidal 30 which has ridges 32, and each having a chamfered upper end 34 and an opposite conical pilot or distal end 36, so that the connected ends 34, 36 form between them a brittle portion 38 of reduced thickness. structure described so far is

  Similarly, it also does not seem necessary to illustrate the proximal end or the extreme handling section which, as before, is analogous to that described above.

  As previously, substantially in the middle of the length of each of the anchoring sections 314, 316 is an enlarged circular body section 318 which is formed by pushing back the anchoring sections 314, 316, in a conventional manner as shown in FIG. 11, the enlarged body portion 318 has a larger diameter than the small diameter 17 and the thread 30 of the remaining threaded portions 314, 316, and therefore the enlarged body portion 318 constitutes a stop member which limits the depth insertion

  anchoring sections 314, 316 in the channel formed in the tooth, as described below by way of example.

  Figure 12 shows at 410 another modified embodiment of the dental anchor 25 according to the invention, substantially similar to the dental anchor 10, having similar threaded anchor sections 414 and 416 each having a helical thread 30 having ridges 32, and each having a chamfered upper end 34 and an opposing conical pilot or distal end 36, such that the connected ends 34, 36 define with each other, as before, a brittle portion 38 of reduced thickness. Therefore, the structure described so far is identical to that previously described for the dental anchoring. In addition, as before, it does not seem necessary to illustrate the proximal end or the extreme handling section which, as before , is identical

to that described above.

  An enlarged upper body portion 418 extends axially between substantially the middle of the length and the upper end of each of the anchor sections 414 and 416, so that the upper body portion 418 is of a length to approximately equal to that of the lower body portion 28 of the anchor sections A chamfered or tapered portion 420 connects each enlarged upper body portion 418 to the lower diameter body portion 28. enlarged upper body 418 comprises threads 422 or grooves 424 constituting means for retaining the suprastructure formed on the toothing. As shown in FIG. 13, the enlarged upper body section 418 has a large diameter of approximately 0.71 mm. which is greater than the small diameter 72 and the thread 30 of the anchor sections 414 and 416 has a large diameter of about 0.61 mm, as previously indicated by

  Accordingly, the enlarged body portion 418 constitutes a stop member for limiting the depth of insertion of the anchor sections 414 and 416 into the channel formed in the tooth, as described below by way of example.

  Figure 14 shows the channels 56 formed in the dentine or body 48 from the excavated surfaces 54 of the tooth 44. As shown, the conventional twist drill 55 is depressed into the dentin in a conventional manner as previously described. each channel having a bottom 68 as indicated above It should again be noted that the dimension 66, representing the large diameter of the pierced channel 56, is smaller than the large diameter of the threaded anchor sections 35 of the aforementioned dental anchors 110, 210, 310 and 410, so that these dental anchors can be automatically screwed into the channel 56 Therefore, the large diameter 66 of the channel 56 is also

  smaller than the large dimensions of body ironcons or stop or stop members 118, 218, 318, 418.

  It should further be noted that the depth of each channel 56 is greater than the distance between the pilot or distal end 36 of each dental anchor and the body portion or stop member 118, 218, 318, 418, for the reason indicated below.

  The insertion of the dental anchors 110, 210, 310 and 410 into the channels 56 of the tooth 44 will now be described by way of example, only the insertion of the anchor being explained, the insertion of the embodiments modified 210, 310 and 410 of the dental anchorage

  being identical and therefore of useless description.

  FIG. 14 is similar to FIGS. 3 and 4 and shows two dental anchors modified according to the invention, inserted on the channels 56 formed in the tooth 44, and a third dental anchor 110 being inserted into a third channel 56 Etant Since the abutment member 118 of the dental anchor 110 bears against the edge of the mouth of the channel 56 when this dental anchor 110 is automatically screwed into the channel, the entry into contact with the edge of the channel opposes the further rotation and triggers the automatic shear mechanism 25 by which the portion 38 or 26 of reduced thickness of the dental anchor 110 -se shears, thus completing the insertion operation of the dental anchor 110 Consequently, the pilot or distal end 36 of the dental anchor 110 does not reach the bottom 68 of the channels 56, the depth of each channel 56 being greater than the distance between the pilot or distal end 36 and the organ e of judgment 118 of

the dental anchor 110.

  Therefore, even if the automatic screwing of the dental anchor 110 is faster and easier to perform than that of the dental anchor 58 of the antrium art, the stresses generated at the bottom 68 of the channels 56 are substantially reduced or eliminated due to the fact that the pilot or distal end 36 of the dental anchor 110 does not reach or does not bear against the bottom 68 due to the presence of the stop member 118 In addition, the shearing of the dental anchor 110 can be more easily provided, since this anchor 110 shears when the stop member 118 bears against the mouth of the channel 56. In addition, when the exposed upper portions of the dental anchor 110 are bent or cut after insertion, and prior to the formation of the suprastructure on the tooth 44, it is evident that the constraints

  produced at the bottom 68 of the channels 56 are minimal or zero.

  Referring now to Figures 16 and 19, there is shown a dental anchor 510 corresponding to another embodiment of the invention.

  The dental anchor 510 has an end portion 512 for handling, an anchored intermediate threaded section 514 and a threaded lower anchor portion 316. The handling end portion 512 is similar in construction to that of the first embodiment shown in FIG. 1. Each of the threaded sections 514 and 516 has a non-threaded body 118 of the type shown in FIG. a diameter greater than the small diameter of the threaded sections and which forms a stop member intended to limit the depth of insertion of the anchoring sections 514 and 516,

as previously described.

  Each of the anchoring sections 514 and 516 has a chamfered upper end 34 and

  an opposing conical pilot or distal end 36.

  The chamfered end 34 has a taper of

   while the chamfered end 36 has a taper of about 200 A reduced thickness portion 26 is disposed between the handling end portion 512 and the anchor threaded portion 516 to form a breakable section therebetween. .

  Similarly, a portion 38 of reduced thickness is defined between the lower and intermediate anchor threaded portions 516 and 514 to form between

  they a second part can be broken.

  The anchoring sections 514 and 516 are similar, and therefore only one of these sections will be described in full. Each of the anchoring sections 514 and 516 comprises a body 118 bearing a helicoidal thread 520. The thread is of the section type. trapezoidal rectangle having a planar upper surface 522

  and an oblique or inclined lower surface 524, separated from each other by a flattened ridge 526.

  The number of threads per centimeter is between 24 and 40, as previously indicated, with 38 threads per centimeter being preferred in the embodiments of Figures 16 to 20, resulting in a pitch of about 0.254 mm. anchoring sections 514 and 516 advantageously have about 8 to 9 threads on each portion of the section above and below the enlarged collar 118, so that the total number of threads per section is between 16 and 18 It should be noted that the figures represent nets whose number is in the overall range

from 24 to 40 per centimeter.

  The angle of the oblique lower surface 524 of each thread is about 45. The small diameter of the pin or pin is about 0.508 mm, the large diameter of the entire pin being about 0, Thus, the depth of each net is about 0.508 mm. The nets are spaced from one another so that there is a small diameter portion between the feet of the adjacent nets. Thus, the threads do not form a continuous sawtooth profile, but they are spaced apart from one another. The height at which the distal end 36 is located with respect to the lowest thread is about 0.208 mm. collar 118 is about

0.254 mm.

  FIG. 20 is an enlarged sectional view of the tooth body 48, similar to that shown in FIG. 5, the section being extended to allow comparison of the dimensions of the first embodiment of the indicated dental anchor. overall in 10 and those of the second embodiment of the dental anchor, indicated overall

in 510.

  The dental anchor 10 of the first embodiment has a small diameter P B of 0.483 Dm and a large diameter GD of 0.61 mm. The normal dimension DT of the hole is 0.533 mm. Therefore, the clearance J between the small diameter and the pierced channel 56 is 0.025 mm. In the anchor 10, a normalized thread having oblique upper and lower edges, advantageously 33 threads per centimeter, according to the invention is used. In the dental anchor 510, a thread is used. of the rectangular trapezoidal section type advantageously comprising 38 threads per centimeter The dental anchor 510 generates a constraint

  reduced in the material of the tooth because the movement of dentin between the adjacent nets is less.

  The small diameter can thus be slightly increased to a value of 0.508 mm. Using the same channel 56 with a diameter of 0.533 nm, one obtains, on each side, between the small diameter and the channel, a set of 0.127 mm The smaller the clearance between the small diameter and the channel, the lower the holding capacity or

  Fixing the dental pin are great.

  It should be noted that while pin 510 of this second embodiment may be less stressful than pin 10 of the first embodiment, a slightly larger number of turns is required to provide pin 510. However, both embodiments require substantially less turns than the prior art pins. The typical prior art pins have about 49 threads per centimeter, which requires at least 10 to 12 threads per centimeter. The embodiments shown in FIG. 16 require only 8 turns to be put in place.

  The manipulation ends of the dental pins according to the invention may have any structure suitable for use with manual or automatic handpieces. As shown in FIG. 17, the end 612 for handling a dental anchor 610 has a tongue The tab 614 may be housed in a conventional manual drive member or in a key. The reduced portion 26 is intended to separate the manipulating end 612 from the stub. lower anchor 618. FIG. 18 shows an end 714 for handling a dental anchor 710 which may comprise a tab 716 made in one piece with the anchoring section 718, without any brittle portion between them. The tab or tab 714 is connected directly to the body 720 of the spindle on which the anchor section 718 is formed. Various types of handling ends may be provided. e used on the anchors, of the invention, such as those described in the patents

  mentioned above and others known in the prior art.

  In the various embodiments

  shown, there is provided a tapered inlet at the front end to facilitate the establishment of the pin 5 and its appropriate housing remote from the bottom of the channel.

  Use of a stop shoulder on various sections

  ensures a complete depth of uniform insertion and guarantees automatic spatter of the spindle.

  The shear points are well defined and give a clear visual indication to accurately see the shear pin. Moreover, by using the trapezoidal thread, the retaining or fixing force is increased, the insertion is accelerated.

  and the displacement of the dentine is reduced.

  It should be noted that the dental anchors 10, 110, 210, 310, 410, 510, 610 and 710 according to the invention, as well as the anterior dental anchor 58, may be made of any suitable material known in the art. in the field of dentistry, such a material encompassing precious metals and metals

  not valuable, or even suitable plastics.

  It goes without saying that many modifications

  can be made to the dental anchor described and shown without departing from the scope of the invention.

Claims (15)

  A dental anchor for insertion into a channel (56) from an excavated surface (54) of a tooth, characterized in that it comprises at least one anchor section (14) having at its end proximal, an extreme portion (12) manipulation allowing it to be coupled to a complementary drive tool, the anchoring section having several self-tightening threads (30) defined by ridges (32) 10 spaced axially, the threaded anchor section having a large diameter greater than the diameter of the channel and a number of threads per centimeter   24 and 40 to ensure fast insertion of the dental anchor in minimal torque.   Dental anchor according to claim 1, characterized in that the anchor section has 33 threads per centimeter and in that the large diameter is about 0.61 mm.   3 Dental anchor according to claim   1, characterized in that the pitch of the threads is 0.305 mm.   4 Dental anchor according to claim   3, characterized in that the anchoring section has a distal pilot end portion (36) elongate in the axial direction and approximately equal to said pitch of the threads.   Dental anchor according to Claim 1, characterized in that the anchoring section has 38 threads per centimeter and in that the large diameter is about 0.61 mm.   Dental anchor according to claim 1, characterized in that the threads have a pitch of 0.254 mm.   Dental anchor according to claim 6, characterized in that the anchoring section has a pilot distal end portion (36) elongate in the axial direction and approximately equal to the pitch of the threads. Dental anchor according to claim 1, characterized in that the threads are of the trapezoidal section.   Dental anchor according to claim 5, characterized in that the anchoring section has a distal pilot end portion (36) elongate in the axial direction and approximately equal to the distance between the nets.   Dental anchor according to claim 9, characterized in that it comprises a second anchored threaded section (16) connected to said distal pilot end portion of the first anchor section cited so that a brittle part (38), of reduced thickness, easily visible, is formed between the two sections. Dental anchor according to claim 1, characterized in that each thread has a   height between 0.051 and 0.064 mm.   Dental anchor according to claim 1, characterized in that the threads have a predetermined pitch and that the distance between the adjacent thread feet is predetermined, this predetermined distance and this predetermined pitch being within a predetermined range. ratio of about 4: 5.   13 Dental anchor according to claim 25, characterized in that the anchoring section comprises stop means arranged along its length in order to limit the depth of insertion of this anchoring section.   in the channel so that the distal pilot end portion of the anchor section can not bear against the bottom 30 of the channel.   14 Dental anchor according to claim 13, characterized in that the stop means are arranged approximately in the middle of the length of the anchoring section. Dental anchor according to claim 13, characterized in that the stop means comprises a non-threaded section (118) having an equal diameter large diameter.   Dental anchor according to claim 13, characterized in that the stop means comprise   a protruding portion (218) having a larger cross-sectional dimension than the large diameter.   17 Dental anchor according to claim   13, characterized in that the stop means comprises a cylindrical section (318) having a larger transverse dimension than the large diameter.   18 Dental anchor according to claim   13, characterized in that the stop means comprise a cylindrical section (418) extending substantially from a midpoint to an opposite end of the anchoring section spaced from said distal pilot end portion, this cylindrical section having a diameter greater than the large diameter.   19 Dental anchor according to claim 18, characterized in that the cylindrical section comprises retaining means for retaining or fixing a suprastructure on the tooth, these retaining means comprising threads (422).   Dental anchor according to claim 18, characterized in that the cylindrical section comprises   retaining means for retaining or attaching a suprastructure to the tooth, said retaining means including grooves (424).